The Home Office figures, published before Christmas, showed a 27% drop in hospital admissions for knife woundings in 10 priority areas. They were criticised as "premature, irregular and selective" by the Whitehall statistics watchdog, Sir Michael Scholar.

The emails show that the NHS chief stastistician, Andy Sutherland, objected to their publication and warned health department officials that it would "look to observers as if the government has cherry picked the good news and forced out publication for political ends - is this really what they want?".

NHS information centre officials added that they were "potentially inaccurate and may possibly give the wrong impression".

Health department officials told them that Number 10 "are adamant about the need to publish this statistic. As a result, I have been informed that they are likely to publish the data irrespective of the concerns raised."

The released emails also disclose that the Number 10 special adviser involved in the affair was Matt Cavanagh, who has worked for the former cabinet minister David Blunkett. The email exchange across Whitehall was triggered by a request from Cavanagh to the Health Department for clearance to publish the figures the next day: "The PM would like us to publish tomorrow."

Cavanagh said that while the figures were only a subset they would make clear that they were provisional and the final figures would be published as national statistics in the usual way.

A letter from the Cabinet minister, Kevin Brennan, to the Commons public administration committee, which released the email trail last night, insisted that the final decision was made by the Home Office.

The shadow home secretary, Chris Grayling, said last night the emails showed a blatant disregard for the rules.